We think of them as the sign of a slow mind, or verbal tics, but do these grunts actually serve a purpose, or even stand in for a useful mental function? Some people think so.
The ‘um,' the ‘uh,' the ‘ah,' and even the Californian ‘like,' have been thoroughly mocked. In some sense, this mockery is deserved. When these things pile up, they can make for an appallingly dull or annoying conversation. But its critics dismiss, what some researchers believe is valuable information. Let's take a look at grunts, and the messages they convey.
Researchers at Stanford and UC Santa Cruz published a paper asserting the claim that ‘um' and ‘uh' are words that serve a conversational, if not strictly linguistic, purpose. One doesn't use them in writing, because a written message allows all the time in the world to formulate a thought. But in conversation, when people understandably have to pause to remember directions, think of names, or pause to re-state a question, they're legitimate conversational signals, and part of how humans communicate. Depending on how they're deployed, they can signal a pause in conversation with the intention of continuing momentarily, a pause meant to signal someone else to speak, or when people want to signal that they're deliberately mulling over a choice.
Responding to a question about who you saw last weekend by saying, for example, "I went out two weeks ago with Katie and, uh, -" signals that you're accessing your memory for a name, and not just trailing off into nothing. Just saying, "Uh," and looking around signals that either you don't care enough to remember, or are asking someone else present to remember for you. Responding to a question about where to go tonight by saying, "X movie," is signaling a strong desire, while, "Uh, X movie," is signaling that you're up for a change of plans. In both cases, ‘uh' isn't just a tic or filler, it communicates something that wouldn't be apparent otherwise.
Brian Christian, in The Most Human Human, points out that this stuff might not even be a weakness. Getting an ‘uh' out before other people do can let you take the lead in speech. Jeopardy contestants do better if they buzz first, when the question sounds familiar, and then access their memories afterwards, making sure that none of their rivals scoop them. The buzz is the equivalent of "Ah!" It's also used in conversations, a sound that precedes thought but makes people pay attention long enough to get the thought out before anyone else does. It's even been suggested that phone trees that insist the caller speaks would be better if they could recognize the pausing and the word ‘um,' as requests for more information or clarification.
Too much of any word makes for annoying reading, as anyone who has thrown a Hemingway book across the room after reading the word ‘fine' one too many times. But pauses, grunts, and verbal exclamations that aren't strictly words still serve communication purposes. Makes me want to go back to the middle school English teacher who ridiculed his students for unconsciously saying the word ‘like,' and wave that paper in his face. And then, like, punch him in the mouth. (You know what I mean.)